AKIPRESS.COM - Ukrainian President Petro Poroshenko has cancelled a visit to Turkey, citing "sharp deterioration in the situation in Donetsk region."

His statement came as pro-Russia rebels took the coast town of Novoazovsk and threatened the strategic port city of Mariupol, in the region's south, according to the media reports.

The rebel successes constitute the opening of a new front in the conflict.

Mr Poroshenko said he was calling a meeting of the Ukrainian security council.

He added that Ukraine would initiate an emergency session of the United Nations Security Council to discuss the crisis.

"I have made a decision to cancel my working visit to the Republic of Turkey due to sharp aggravation of the situation in Donetsk region... as Russian troops were actually brought into Ukraine," Mr Poroshenko's statement said.

Government forces had made significant advances against the separatists in recent weeks, but these gains seem in doubt with rebels now operating in two distinct areas of Donetsk region.